One of the many uses of cellulose fibers is as a reinforcing material in cementitious products, such as those containing concrete, chalk, asphalt, bitumen, plaster, cement, gypsum, mortar, and the like. Cellulose fibers for use in these materials are typically supplied from commercially available market pulp sheets. Some pulp sheets are rolls of lightly pressed fluff pulp sheets. Other market pulp is papergrade, which is a more tightly pressed sheet. In order for cellulose fibers from a pulp sheet to be more fully assimilated within the cementitious product, the sheets must first be broken up with the use of a mechanical device, typically a hammermill, that fiberizes the sheet into singulated pulp fibers. The pulp fibers are then added to the product. Sometimes the market pulp sheet is diced and the diced pulp sheet is added. Papergrade pulp sheet being more densified than fluff pulp sheet, consequently is more difficult to disperse (has longer dispersion time) in wet media than fluff pulp sheet. In attempts to improve the dispersibility, either type of pulp sheet can be hammermilled or diced. However, once singulated into individual fibers, the fibers are considered to be undesirable because of their inability to be metered. Some pulp sheets, especially of the fluff type, are more readily dispersible. Sheets, however, are incapable of flowing in conduits and are too large to be metered in precise quantities for cementitious products. Dicing pulp sheet is also undesirable, since dicing, like hammermilling, requires additional processing prior to dispersing the fibers. Dicing also leads to localized highly densified areas or “edge effects” at the shear points that reduces the capacity of those densified areas of the fibers to disperse. The disadvantages of pulp sheet makes finding a new form of cellulose having none of the aforementioned drawbacks more urgent. U.S. Pat. Nos. 5,407,139 and 6,345,777 describe mechanically refiberizing cellulose products prior to their application in asphalt and cement. Refiberizing the cellulose materials immediately prior to application adds unwanted complexity and cost to the structures built from these materials. U.S. Pat. No. 5,931,610 describes a method for mechanically breaking up clumps of synthetic fibers. German publication Offenlegungschrift DE 100 09152A1 describes making dense cellulose and synthetic fiber pellets.
It would be advantageous to provide a fibrous cellulose product that does not require mechanical fiberizing of the fiber source once dried. Ideally, such product would be easier to meter much better than singulated fibers. It is also desirable that the new fibrous product have a wet dispersability comparable to the presently available pulp sheets, but that avoids the need for hammermilling. The present invention fulfills these needs and provides further related advantages.